Exploring Deep Ocean Habitats

Species Profile – Bamboo coral

On our dive two days ago we brought up a beautiful sample of Bamboo coral. The dark bands on a light-colored background give this coral its common name.

Bamboo coral skeletons consist of stretches of light-colored branch-like calcium carbonate material, interspersed with darker joint-like regions of gorgonin protein. The black bands may serve as shock absorbers or as flexibility joints – you don’t normally see organisms with a carbonate skeleton getting that large.

The specimen collected was fairly large (~2 ft) so it was attached to the outside of the ROV with a bungee cord by one of the manipulator arms. A large specimen is needed in order to have enough girth at the base to section it for age determination. Brendan Roark explained that he uses them for paleoclimate studies since some of these deep-water corals can live for several hundred years. Back in his laboratory, Brendan will cut disks from bottom and analyze the age of this coral much like you can do with tree rings.

The black bands in bamboo coral may act as shock absorbers or flexible joints. Photo by Mike Dunn.

Another unique thing about these corals is their banded structure – the same organism is depositing two distinct types of skeletons. The light-colored carbonate portion derives its carbon from in situ organic carbon at the depth at which the organism is living whereas the black bands are getting their carbon from marine snow (particulate organic matter recently exported from surface waters). It’s like having two history books side by side. So you can compare the radiocarbon profile from the two different portions of the same bamboo coral and it may be able to tell you what was going on at the surface and at depth over its long life-span.

When tissue samples were collected on deck, the bamboo coral bioluminesced. Photo by R. Peyton Hale.

There are even bioluminescent bamboo corals that give off a blue light that shoots up and down the axis when touched. Much is still being learned about these fascinating corals. Recently, a mission funded by NOAA discovered seven new species of bamboo coral in deep waters off the Hawaiian Islands. Of these seven new species, six may represent completely new genera.